Expandable fusion device and method of installation thereof

ABSTRACT

The present invention provides an expandable fusion device capable of being inserted between adjacent vertebrae to facilitate the fusion process. A method of installing an expandable fusion device may comprise introducing the expandable fusion device into an intervertebral space, wherein the expandable fusion device comprises a proximal end, a distal end, an anterior side connecting the proximal end and the distal end, and a posterior side connecting the proximal end and the distal end, wherein the expandable fusion device has an anterior height on the anterior side and a posterior height on the posterior side. The method may further comprise adjusting the anterior height of the expandable fusion device independently from adjustment of the posterior height. The method can also include changing the lordotic angle.

FIELD OF THE INVENTION

The present invention relates to the apparatus and method for promotingan intervertebral fusion, and more particularly relates to an expandablefusion device capable of being inserted between adjacent vertebrae tofacilitate the fusion process.

BACKGROUND

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc may first be partially orfully removed. Typically, an intervertebral fusion device may then beinserted between neighboring vertebrae to maintain normal disc spacingand restore spinal stability, thereby facilitating an intervertebralfusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, two important factors inintervertebral fusion may be the anterior (lordotic) angle adjustmentand posterior height adjustment. The lordotic angle may be important inrestoring sagittal balance while the posterior height may aid inrestoring disc height and indirect decompression of the neural foramen.While convention fusion devices may allow for in-situ expansion, they donot allow for the lordotic angle and posterior height to be adjustedin-situ independently of one another.

SUMMARY

In an exemplary embodiment, the present invention provides an expandablefusion device comprising a first endplate and first ramp frames that arepivotally coupled to the first endplate. The expandable fusion devicemay further comprise a second endplate and second ramp frames that arepivotally coupled to the second endplate. The expandable fusion devicemay further comprise a translation member assembly in engagement withthe first ramp frames and the second ramp frames, the translation memberassembly comprising ramps on a first side of the expandable fusiondevice and ramps on a second side of the expandable fusion device. Theexpandable fusion device may further comprise a first actuation memberin engagement with the translation member assembly on the first side ofthe expandable fusion device. The expandable fusion device may furthercomprise a second actuation member in engagement with the translationmember assembly on the second side of the expandable fusion device.

In an exemplary embodiment, the present invention provides an expandablefusion device comprising a first endplate and a second endplate. Theexpandable fusion device may further comprise a translation memberassembly disposed at least partially between the first endplate and thesecond endplate. The translation member assembly may comprise ananterior translation portion disposed on an anterior side of theexpandable fusion device, wherein the anterior translation portioncomprises one or more ramps. The translation member assembly may furthercomprise a posterior translation portion in engagement with the anteriortranslation portion, wherein the posterior translation portion isdisposed on a posterior side of the expandable fusion device, whereinthe posterior translation portion is slidable with respect to theanterior translation portion, wherein the posterior translation portioncomprises one or more ramps. The translation member assembly may furthercomprise an anterior ramped end disposed on the anterior side of theexpandable fusion device and at a proximal end of the expandable fusiondevice. The translation member assembly may further comprise a posteriorramped end in engagement with the anterior ramped end, wherein theposterior ramped end is disposed on the posterior side of the expandablefusion device and at the proximal end of the expandable fusion device,wherein the posterior ramped end is slidable with respect to theanterior ramped end. The expandable fusion device may further comprise afirst actuation screw threaded through a bore in the anterior ramped endand engaging the anterior translation portion. The expandable fusiondevice may further comprise a second actuation screw threaded through abore in the posterior ramped end and engaging the posterior translationportion. The expandable fusion device may further comprise anterior rampframes disposed on the anterior side of the expandable fusion devicethat engage the ramps in the anterior translation portion to transfermotion of the anterior translation portion to the first endplate and thesecond endplate thereby pushing the first endplate and the secondendplate outward increasing an anterior height of the expandable fusiondevice. The expandable fusion device may further comprise posterior rampframes disposed on the posterior side of the expandable fusion devicethat engage the ramps in the posterior translation portion to transfermotion of the posterior translation portion to the first endplate andthe second endplate thereby pushing the first endplate and the secondendplate outward increasing a posterior height of the expandable fusiondevice.

In an exemplary embodiment, the present invention provides a method ofinstalling an expandable fusion device. The method may compriseintroducing the expandable fusion device into an intervertebral space,wherein the expandable fusion device comprises a proximal end, a distalend, an anterior side connecting the proximal end and the distal end,and a posterior side connecting the proximal end and the distal end,wherein the expandable fusion device has an anterior height on theanterior side and a posterior height on the posterior side. The methodmay further comprise adjusting the anterior height of the expandablefusion device independently from adjustment of the posterior height. Themethod may further comprise adjusting the posterior height of theexpandable fusion device.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present disclosure.

FIG. 2 is a perspective view of an embodiment of an expandable fusiondevice according to the present disclosure.

FIG. 3 is an end view of an embodiment of the expandable fusion deviceof FIG. 2.

FIG. 4 is end view of an embodiment of an endplate of the expandablefusion device of FIG. 2 showing a pivot point.

FIG. 5 is another end view of an embodiment of an endplate of theexpandable fusion device of FIG. 2 showing a pivot point.

FIG. 6 is a perspective view of an embodiment of a translation memberassembly of the expandable fusion device of FIG. 2.

FIG. 7 is a perspective view of an expansion fusion device according toanother embodiment of the present disclosure.

FIG. 8 is another view of an embodiment of the expandable fusion deviceof FIG. 7.

FIG. 9 is an end view of an embodiment of the expandable fusion deviceof FIG. 7.

FIG. 10 is a top view of an embodiment of the expandable fusion deviceof FIG. 7.

FIG. 11 illustrate an expandable fusion device according to anotherembodiment of the present disclosure.

FIG. 12 illustrate an expandable fusion device according to anotherembodiment of the present disclosure.

FIG. 13 illustrates an expandable fusion device according to anotherembodiment of the present disclosure.

FIG. 14 is a cross-sectional view of the expandable fusion device ofFIG. 13 taken along line a-a.

FIG. 15 is a cross-sectional view of the expandable fusion device ofFIG. 13 taken along line b-b

FIGS. 16A and 16B are end views of an embodiment of an endplate of theexpandable fusion device of FIG. 13 showing a pivot point.

FIG. 17 is a close-up view of an embodiment the endplate of FIGS. 16Aand 16B taken along circle 17.

FIG. 18 is a side view of an embodiment of the endplate of FIGS. 16A and16B showing contact with a ramped translation member.

FIG. 19 is an end view of an expandable fusion device according toanother embodiment of the present disclosure.

FIG. 20 is a cross-sectional view of the expandable fusion device ofFIG. 19 taken along line c-c.

FIG. 21 is a cross-sectional view of the expandable fusion device ofFIG. 20 taken along line d-d.

FIGS. 22 and 23 are end views of an expandable fusion device accordingto another embodiment of the present disclosure.

FIGS. 24 and 25 are end views of an expandable fusion device accordingto another embodiment of the present disclosure.

FIG. 26 is a perspective view of a translation member assembly in theform of translating bar according to another embodiment of the presentdisclosure.

FIGS. 27-29 illustrate end views of a translation member assembly thatincorporates side wedges according to another embodiment of the presentdisclosure.

FIGS. 30-33 illustrate a corpectomy device according to anotherembodiment of the present disclosure.

FIGS. 34 and 35 illustrate another technique for expansion of anexpandable fusion device according to the present disclosure.

FIGS. 36 and 37 illustrate another technique for expansion of anexpandable fusion device according to the present disclosure.

FIGS. 38 and 39 illustrate another technique for expansion of anexpandable fusion device according to the present disclosure.

FIG. 40 illustrates a perspective view an expandable fusion deviceaccording to another embodiment of the present disclosure.

FIG. 41 illustrates a perspective view an expandable fusion deviceaccording to another embodiment of the present disclosure.

FIG. 42 is a cross-sectional view of an embodiment of the expandablefusion device of FIG. 41 taken along plane 42.

FIGS. 43-45 illustrate embodiments for expansion of the expandablefusion device of FIG. 41.

FIG. 46 is a cross-sectional view of an expandable fusion deviceaccording to another embodiment of the present disclosure.

FIGS. 47-49 illustrate another technique for expansion of an expandablefusion device according to the present disclosure.

FIGS. 50-54 illustrate another technique for expansion of an expandablefusion device according to the present disclosure.

DETAILED DESCRIPTION

The following description of certain embodiment(s) is merely exemplaryin nature and is in no way intended to limit the invention, itsapplication, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disk material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an exemplary embodiment of an expandable fusiondevice 10 is shown between adjacent vertebral bodies 15 and 20. Theexpandable fusion device 10 may be implanted between two adjacentvertebral bodies 15 and 20 in any section of the spine, including thecervical, thoracic, lumbar, and sacral vertebral sections. More than oneexpandable fusion device 10 may be implanted within the body, forexample, between successive or separated vertebrae. As illustrated, theexpandable fusion device 10 engages the endplates 25 and 30 of theadjacent vertebral bodies 15 and 20 and, in the installed position,maintains normal intervertebral disc spacing and restores spinalstability, thereby facilitating an intervertebral fusion. The expandablefusion device 10 can be manufactured from a number of materialsincluding titanium, stainless steel, titanium alloys, non-titaniummetallic alloys, polymeric materials, plastics, plastic composites,PEEK, ceramic, and elastic materials. In an embodiment, the expandablefusion device 10 can be configured to be placed down an endoscopic tubeand into the disc space between the adjacent vertebral bodies 15 and 20.

As illustrated, the expandable fusion device 10 may have an anteriorside 35 and a posterior side 40. As will be discussed in more detailbelow, expansion of the expandable fusion device 10 may be controlled sothat the anterior height H_(a) and the posterior height H_(p) may beindependently controlled. By way of example, the expandable fusiondevice 10 may have independent anterior expansion and posteriorexpansion mechanisms. By separate control of anterior expansion andposterior expansion, an operator may adjust the expandable fusion device10 to provide a desired amount of posterior height H_(p) and lordoticangle θ. Those of ordinary skill in the art will appreciate that thelordotic angle θ is dependent on the anterior height H_(a) and posteriorheight H_(p) of the expandable fusion device 10. In some embodiments,expansion on the anterior side 35 and the posterior side 40 may also beperformed simultaneously to maintain a lordotic angle θ with onlychanging the anterior height H_(a) and the posterior height H_(p) at thesame rate. While the expandable fusion device 10 is described hereinusing several varying embodiments, the expandable fusion device 10should not be limited to these embodiments.

In some embodiments, the expandable fusion device 10 may be configuredand sized to be placed down an insertion tube and into the disc spacebetween the adjacent vertebral bodies 15 and 20. For example, expandablefusion device 10 may be configured for insertion through an insertiontube, such as, e.g., a cannula. It should be noted, however, that theinsertion tube may alternatively have any suitable diameter. In oneembodiment, expandable fusion device 10 may be inserted through acannula having a diameter of about 8.5 mm. In some embodiments, theexpandable fusion device 10 may have a width in a range of from about 8mm to about 26 mm, and a length in a range from about 20 mm to about 65mm, or may have other suitable dimensions. Expandable fusion device 10may be inserted into a patient via a direct lateral procedure, althoughanterior, anterolateral, posterolateral or posterior proceduresalternatively may be utilized.

Expandable fusion device 10 may have an anterior height H_(a) andposterior height H_(p) that are independently adjustable. In someembodiments, the anterior height H_(a) and posterior height H_(p) mayeach be independently expanded to a height that is equal to or greaterthan about 150% of their respective initial heights. In one embodiment,the anterior height H_(a) and posterior height H_(p) may each beindependently expanded to a height that is equal to or greater thanabout 200% of their respective initial heights, or another suitablepercentage of their respective initial height.

In some embodiments, bone graft or similar bone growth inducing materialcan be introduced around and within the expandable fusion device 10 tofurther promote and facilitate the intervertebral fusion. The expandablefusion device 10, in one embodiment, may be packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the expandable fusion device 10. Such bone graft maybe packed between the endplates of the adjacent vertebral bodies 15 and20 prior to, subsequent to, or during implantation of the expandablefusion device 10.

In some embodiments, the expandable fusion device 10 may be treated witha titanium and/or hydroxyapatite plasma spray coating to encourage bonyon-growth, improving the strength and stability of the connectionbetween the respective component and the underlying bone (e.g., avertebral body). Any other suitable coating also may be provided onexpandable fusion device 10. Such coatings may include therapeuticagents, if desired. Expandable fusion device 10 also may includeradiopaque markings to facilitate in vivo visualization. In someembodiments, portions of expandable fusion device 10 may be formed of aradiolucent material, while other portions of expandable fusion device10 may be formed of radiopaque materials to facilitate imaging of theradiopaque portions of expandable fusion device 10, such as, e.g.,actuating mechanisms, endplates, ramps, or the like.

With reference now to FIGS. 2 and 3, an embodiment of the expandablefusion device 10 is shown. In an exemplary embodiment, the expandablefusion device 10 includes a first endplate 45, a second endplate 50, anda translation member assembly 55, The expandable fusion device 10 mayalso include a plurality of ramp frames that transfer motion of thetranslation member assembly 55 to the first endplate 45 and secondendplate 50. In the illustrated embodiment, the expandable fusion device10 may comprise a first anterior ramp frame 60 for engaging the firstendplate 45 on anterior side 35. The expandable fusion device 10 mayalso comprise a second anterior ramp frame 65 for engaging the secondendplate 50 on anterior side 35. The expandable fusion device 10 mayalso comprise a first posterior ramp frame 70 for engaging the firstendplate on posterior side 40. The expandable fusion device 10 may alsocomprise a second posterior ramp frame (not shown) for engaging thesecond endplate 50 on posterior side 40. The expandable fusion device 10may also comprise an actuation member, such as first actuation screw 75,for controlling anterior height H_(a) and a second actuation member,such as second actuation screw 80, for controlling posterior heightH_(p). It should be recognized that terms anterior and posterior areused to represent anatomical locations with respect to a patient.Accordingly, the terms anterior and posterior when used with respect tothe expandable fusion device 10 should not be limited to the specificside shown, as the directions anterior and posterior may changedepending, for example, on the direction of insertion.

Expandable fusion device 10 may form a distal end 85 which may beinserted first into the patient's body, and which may be tapered tofacilitate insertion between adjacent vertebral bodies 15 and 20.Expandable fusion device 10 may also form a proximal end 90 to which aninsertion device (not shown) may be connected. Expandable fusion device10 may be inserted in a collapsed configuration that is smaller than anexpanded configuration. In the expanded configuration, the anteriorheight H_(a) and/or posterior height H_(p) has been increased.Expandable fusion device 10 may be moveable from the collapsedconfiguration to the expanded configuration.

With additional reference to FIGS. 4 and 5, the first endplate 45 willnow be described in more detail. Although the following discussionrelates to the first endplate 45, it should be understood that it alsoequally applies to the second endplate 50 as the second endplate 50 issubstantially identical to the first endplate 45 in embodiments of thepresent invention. In the illustrated embodiment, first endplate 45 maycomprise an outer surface 95 extending from distal end 85 to proximalend 90. While not illustrated, in an exemplary embodiment, the outersurface 95 may include texturing to aid in gripping the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections. First endplate 45 may also comprisean anterior endplate side 100 and a posterior endplate side 105.Anterior endplate side 100 may be disposed at anterior side 35 ofexpandable fusion device 10. Posterior endplate side 105 may be disposedat posterior side 40 of expandable fusion device 10. As best seen onFIG. 4, first endplate 45 may also comprise an inner surface 110.

First endplate 45 may engage first anterior ramp frame 60 and firstposterior ramp frame 70. First endplate 45 may include a first matingfeature 115 and a second mating feature 120. The first mating feature115 and second mating feature 120 First mating feature 115 and secondmating feature 120 may form joints with corresponding mating features125 and 130 of the first anterior ramp frame 60 and the first posteriorramp frame 70. The joints formed by engagement of first mating feature115 and second mating feature 120 with corresponding mating features 125and 130 may form pivot points to facilitate independent expansion ofanterior side 35 and posterior side 40. First mating feature 115 andsecond mating feature 120 may be balls, tongue or otherwise formedprotrusions to allow pivoting of first endplate 45 with respect to firstanterior ramp frame 60 and first posterior ramp frame 70. For example,first mating feature 115 may pivot in corresponding mating feature 125of first anterior ramp frame 60. First mating feature 115 and secondmating feature 120 may also allow sliding of first endplate 45 withrespect to first anterior ramp frame 60 and/or first posterior rampframe 70. For example, second mating feature 120 may be pivot and slidein corresponding mating feature 130 of first posterior ramp frame 70. Inthe illustrated embodiment, the first mating feature 115 and secondmating feature 120 may be in the form of a ball, tongue, or otherprotrusion that mates with corresponding mating features 125 and 130,which may be in the form of a recess, groove, or otherwise formedopening.

In some embodiments, the first endplate 45 and second endplate 50 mayfurther comprise through openings 135. Through opening 135 is shown infirst endplate 45 on FIG. 2. The through openings 135 may form anopening that extends from outer surface 95 to inner surface 110. Thethrough openings 135, in an exemplary embodiment, may be sized toreceive bone graft or similar bone growth inducing material and furtherallow the bone graft or similar bone growth inducing material to bepacked in a central opening (not shown) of the expandable fusion device10.

Turning now to FIG. 6, translation member assembly 55 will now bedescribed in more detail. In the illustrated embodiment, translationmember assembly 55 may comprise an anterior translation portion 140, aposterior translation portion 145, an anterior ramped end 150, and aposterior ramped end 155. The anterior translation portion 140 andanterior ramped end 150 may be disposed on anterior side 35 ofexpandable fusion device 10. The posterior translation portion 145 andposterior ramped end 155 may be disposed on posterior side 40 ofexpandable fusion device 10. Anterior ramped end 150 and posteriorramped end 155 may be disposed on proximal end 90 of the expandablefusion device 10. Anterior ramped end 150 and posterior ramped end 155may moveable in the direction indicated by arrows 160 and 165. Theanterior translation portion 140 and posterior translation portion 145may be moveable in the direction indicated by arrows 170 and 175. Theanterior translation portion 140, posterior translation portion 145,anterior ramped end 150, and posterior ramped end 155 may engage thecorresponding ramp frame to cause expansion of the expandable fusiondevice. For example. anterior translation portion 140 and anteriorramped end 150 may be moveable to engage first anterior ramp frame 60and second anterior ramp frame 65, thus casing first anterior ramp frame60 to push outwardly on first endplate 45 and second anterior ramp frame65 to push outwardly on second endplate 50. In this manner, anteriorside 35 of expandable fusion device may be expanded/contracted byengagement of anterior translation portion 140 and anterior ramped end150 with first anterior ramp frame 60 and second anterior ramp frame 65.By way of further example, posterior translation portion 145 andposterior ramped end 155 may be moveable to engage first posterior rampframe 70 and second posterior ramp frame, thus casing first posteriorramp frame 70 to push outwardly on first endplate 45 and secondposterior ramp frame to push outwardly on second endplate 50. In thismanner, posterior side 40 of expandable fusion device may beexpanded/contracted by engagement of posterior translation portion 145and posterior ramped end 155 with first posterior ramp frame 70 andsecond anterior ramp frame.

Anterior translation portion 140 may comprise a first end 180 and asecond end 185. As illustrated, a connecting bar 190 may extend fromfirst end 180 to second end 185. First end 180 may include a bore 195,which may be threaded, for receiving first actuation screw 75. Anteriortranslation portion 140 may further comprise one or more ramps, such asramps 200, 205, 210, that are configured to engage first anterior rampframe 60 and second anterior ramp frame 65 and transfer movement of theanterior translation portion 140 thereto. Ramp 200 may be disposed atfirst end 180, ramp 205 may be disposed on connecting bar 190, and ramp210 may be disposed on second end 185.

Posterior translation portion 145 may comprise a first end 215 and asecond end 220. As illustrated, a connecting bar 226 may extend fromfirst end 215 to second end 220. First end 215 may include a bore 225,which may be threaded, for receiving second actuation screw 80.Posterior translation portion 145 may further comprise one or moreramps, such as ramps 230, 235, 240 that are configured to engage firstposterior ramp frame 70 and second posterior ramp frame and transfermovement of the posterior translation portion 145 thereto. Ramp 230 maybe disposed at first end 215, ramp 235 may be disposed on connecting bar226, and ramp 240 may be disposed on second end 220.

Anterior translation portion 140 may engage posterior translationportion 145. In some embodiments, anterior translation portion 140 mayslidingly engage posterior translation portion 145, for example, with adovetail or other suitable sliding joint. As illustrated, anteriortranslation portion 140 may comprise a flange 245 or other suitableprotrusion at second end 185 that may be received in a slot 250 atsecond end 220 of posterior translation portion 145. The flange 245 mayhave an enlarged edge (not shown) to prevent removal of flange 245 fromslot. As further illustrated, anterior translation portion 140 mayfurther comprise a protrusion 255 (e.g., tongue) at first end 180 Theflange 245 and slot 250 may form a sliding and interlocking joint thatallows translation of the anterior translation portion 140 and theposterior translation portion 145 with respect to one another. that maybe received in a groove 260 at first end 215 of posterior translationportion 145. The protrusion 255 and groove 260 may form a sliding andinterlocking joint that also allows translation of the anteriortranslation portion 140 and the posterior translation portion 145 withrespect to one another.

Anterior ramped end 150 may comprise a body portion 265. Body portion265 may comprise ramp 270 and bore 275. Ramp 275 may be configured toengage first anterior ramp frame 60 and second anterior ramp frame 65and transfer movement of the anterior ramped end 150 thereto. Bore 275may be threaded for receiving first actuation screw 75. Anterior rampedend 150 may be coupled to anterior translation portion 140 via firstactuation screw 75.

Posterior ramped end 155 may comprise a body portion 280, which maycomprise ramp 285 and bore 290. Ramp 285 may be configured to engagefirst posterior ramp frame 70 and second anterior ramp frame andtransfer movement of the posterior ramped end 155 thereto. Bore 290 maybe threaded for receiving second actuation screw 80. Posterior rampedend 155 may be coupled to posterior translation portion 145 via secondactuation screw 80. Posterior ramped end 155 may engage anterior rampedend 150, for example, via a sliding connection, such as dovetailconnection 295.

A method of installing the expandable fusion device 10 of FIGS. 1-6 isnow discussed in accordance with exemplary embodiments. Prior toinsertion of the expandable fusion device 10, the intervertebral spacemay be prepared. In one method of installation, a discectomy may beperformed where the intervertebral disc, in its entirety, is removed.Alternatively, only a portion of the intervertebral disc can be removed.The endplates of the adjacent vertebral bodies 15 and 20 may then bescraped to create an exposed end surface for facilitating bone growthacross the intervertebral space. One or more endoscopic tubes may thenbe inserted into the disc space. The expandable fusion device 10 maythen be introduced into the intervertebral space down an endoscopic tubeand seated in an appropriate position in the intervertebral disc space.

After the expandable fusion device 10 has been inserted into theappropriate position in the intervertebral disc space, the expandablefusion device 10 can then be expanded into the expanded configuration.As previously described, expansion of the anterior side 35 and posteriorside 40 may be independently controlled. For example, the anterior side35 and posterior side 40 may be separately expanded at different times,expanded at different rates, and/or expanded at the rate (e.g., tomaintain a desired lordotic angle θ). To expand the anterior side 35 ofthe expandable fusion device 10, the anterior ramped end 150 andanterior translation portion 140 may be moved with respect to oneanother. For example, the anterior ramped end 150 may be moved towardanterior translation portion 140 in direction indicated by arrow 165. Byway of further example, anterior translation portion 140 may be movedtoward anterior ramped end 150 in direction indicated by arrow 170. Orboth the anterior ramped end 150 and anterior translation portion 140may be moved toward one another. As the anterior ramped end 150 andanterior translation portion 140 move with respect to one another, theypush against the corresponding first anterior ramp frame 60 and secondanterior ramp frame 65, which in turn push against the first endplate 45and second endplate 50 to cause an increase in anterior height H_(a). Toexpand the posterior side 40 of the expandable fusion device 10, theposterior ramped end 155 and posterior translation portion 145 may bemoved with respect to one another. For example, the posterior ramped end155 may be moved toward posterior translation portion 145 in directionindicated by arrow 160. By way of further example, posterior translationportion 145 may be moved toward posterior ramped end 155 in directionindicated by arrow 175. Or both the posterior ramped end 155 andposterior translation portion 145 may be moved toward one another. Asthe posterior ramped end 155 and posterior translation portion 145 movewith respect to one another, they push against the corresponding firstposterior ramp frame 70 and second posterior ramp frame, which in turnpush against the first endplate 45 and second endplate 50 to cause anincrease in posterior height H_(p).

In the event the expandable fusion device 10 needs to be repositioned orrevised after being installed and expanded, the expandable fusion device10 can be contracted back to the unexpanded configuration, repositioned,and expanded again once the desired positioning is achieved. To contractthe expandable fusion device 10, the above-described procedure may bereversed. By way of example, for contraction of anterior side 35, theanterior ramped end 150 and anterior translation portion 140 may bemoved with away from one another using first actuation screw 75. Forcontraction of posterior side 40, the posterior ramped end 155 andposterior translation portion 145 may be moved with away from oneanother using second actuation screw 80.

First actuation screw 75 or another other suitable actuation mechanismmay be used to facilitate expansion of anterior side 35. As previouslydescribed, first actuation screw 75 may be disposed in bore 275 ofanterior ramped end 150 and bore 195 of anterior translation portion140. When first actuation screw 75 is rotated in a first direction, theanterior ramped end 150 and anterior translation portion may be drawncloser together. When first actuation screw 75 is rotated in a seconddirection (opposite the first direction), the anterior ramped end 150and anterior translation portion 140 may move away from one another.

Second actuation screw 80 or another other suitable actuation mechanismmay be used to facilitate expansion of posterior side 40. As previouslydescribed, second actuation screw 80 may be disposed in bore 290 ofposterior ramped end 155 and bore 225 of posterior translation portion145. When second actuation screw 80 is rotated in a first direction, theposterior ramped end 155 and posterior translation portion 145 may bedrawn closer together. When second actuation screw 80 is rotated in asecond direction (opposite the first direction), the posterior rampedend 155 and posterior translation portion 145 may move away from oneanother.

With reference now to FIGS. 7-11, an expandable fusion device 10 is showaccording to another embodiment. As illustrated, the expandable fusiondevice 10 may comprise an anterior side 35 and a posterior side 40. Inthe illustrated embodiment, the expandable fusion device 10 comprises apair of expandable implants, illustrated as anterior expandable implant300 and posterior expandable implant 305, respectively. The anteriorexpandable implant 300 comprise a pair of opposing anterior endplates310 and the posterior expandable implant 305 comprises a pair ofopposing posterior endplates 315. The anterior endplates 310 and theposterior endplates 315 may be expanded independently allowing controlof height on each side of expandable fusion device 10. The resultantlordotic angle θ may be based on the difference in height between theanterior expandable implant 300 and the posterior expandable implant305. The anterior expandable implant 300 may be secured to the posteriorexpandable implant 305. By way of example, a connecting bar 320 mayattach the anterior expandable implant 300 to the posterior expandableimplant 305.

FIG. 9 illustrates a front end view of expandable fusion device 10 withanterior endplates 310 expanded. As illustrated, the anterior expandableimplant 300 and posterior expandable implant 305 may share a front (ordriving) ramp 325. Bores 330 and 335 may be formed in front ramp 325through which first actuation screw 75 and second actuation screw 80 maybe disposed. Anterior expandable implant 300 may be expanded by rotationof first actuation screw 75, and posterior expandable implant 305 may beexpanded by rotation of second actuation screw 80. As the firstactuation screw 75 rotates, anterior ramps (not shown) may be drawn tofront ramp 325, while anterior ramps and front ramp 325 engage anteriorendplates 310 causing expansion of anterior expandable implant 300. Asthe second actuation screw 80 rotates, posterior ramps (not shown) maybe drawn to front ramp 325, while posterior ramps and front ramp 325engage posterior endplates 315 to cause expansion of posteriorexpandable implant 305. Front ramp 325 may further comprise a graft hole340. As illustrated, graft hole 340 may be disposed between bores 330and 335. Graft hole 340 may be sized to receive bone graft or similarbone growth inducing material and further allow the bone graft orsimilar bone growth inducing material to be packed in a central opening(not shown) of the expandable fusion device 10.

FIG. 10 illustrates a top view of expandable fusion device 10 withanterior endplates 310 expanded. As illustrated, connecting bar 320 maysecure anterior expandable implant 300 and posterior expandable implant305. In some embodiments, connecting bar 320 may be rigidly attached tonose 345 of posterior expandable implant 305. The connecting bar 320 maybe housed within a center shaft 350 on anterior expandable implant 300and may translate as anterior expandable implant 300 may be expanded orcollapsed.

Any suitable technique may be used for expansion of anterior expandableimplant 300 and posterior expandable implant 305. One technique forexpansion of anterior expandable implant and posterior expandableimplant 305 may be provided in U.S. Patent Publication No. 2014/0067071,the disclosure of which in incorporated herein by reference. While notillustrated, the anterior expandable implant 300 and posteriorexpandable implant 305 may each comprise a central ramp. The centralramps may include ramps that engage anterior endplates 310 and theposterior endplates 315. For expansion of anterior side 35, the firstactuation screw 75 may be rotated to draw the central ramp of theanterior expandable implant 300 and the front (or driving) ramp 325closer together, for example, by pulling the central ramp toward thefront ramp 325. The central ramp and front ramp 325 may engage theanterior endplates 310 forcing them apart. While not shown the centralramp and front ramp 325 may comprise ramps that engage correspondingramps in the anterior endplates 310. For expansion of posterior side 40,the second actuation screw 80 may be rotated to draw the central ramp ofthe posterior expandable implant 305 and the front (or driving) ramp 325closer together, for example, by pulling the central ramp toward thefront ramp 325. The central ramp and front ramp 325 may engage theposterior endplates 315 forcing them apart. While not shown the centralramp and front ramp 325 may comprise ramps that engage correspondingramps in the posterior endplates 315.

While the preceding description provides discusses techniques tofacilitate expansion it should be understood that the present disclosureshould not be limited to these techniques. Any suitable technique forfacilitating independent expansion of anterior side 35 and posteriorside 40 of expandable fusion device 10 may be used. The followingdescription of FIGS. 11-54 provide alternative expansion techniques thatmay be used to facilitate expansion of an anterior side 35 and posteriorside 40 of an expandable fusion device.

Referring now to FIG. 11, expandable fusion device 10 is shown accordingto another embodiment. In the illustrated embodiment, expandable fusiondevice 10 comprises first endplate 45 and second endplate 50. Asillustrated, the expandable fusion device 10 may further comprise anactuation screw 355 coupled to a ball bearing 360. The actuation screw355 and ball bearing 360 may be disposed between the first endplate 45and the second endplate 50. Rotation of actuation screw 355 would in inturn drive ball bearing 360. The ball bearing 360 may be moved back andforth between the first endplate 45 and second endplate 50 to adjustheight. The first endplate 45 and second endplate 50 may be coupled tohinges 365. As height of the expandable fusion device 10 may beadjusted, the first endplate 45 and second endplate 50 may pivot athinges 365. While not shown, the hinges 365 may be fixed to a frame.

FIG. 12 illustrates expandable fusion device 10 according to anotherembodiment. As illustrated, expandable fusion device 10 may comprisefirst endplate 45 and second endplate 50. The expandable fusion device10 may further comprise a frame 370. The frame 370 may have walls thatare angled, tapered, or otherwise formed. In the illustrated embodiment,the first endplate 45 and second endplate 50 may each have lips 375 thatmay overlap frame 370 and thereby prevent the first endplate 45 andsecond endplate 50 from dislocating. The first endplate 45 and secondendplate 50 may move freely within the frame 370, allowing theexpandable fusion device 10 to expand or contract while the firstendplate 45 and second endplate 50 may conform to anatomy of theadjacent vertebral bodies 15 and 20.

FIGS. 13-15 illustrate expandable fusion device 10 according to anotherembodiment. FIG. 14 is a cross-sectional view of FIG. 13 taken alongline a-a. FIG. 15 is a cross-sectional view of FIG. 13 taken along lineb-b. In the illustrated embodiment, expandable fusion device 10 maycomprise a first endplate 45 and a second endplate 50. Expandable fusiondevice 10 may further comprise a rear plate 380 through which a firstactuation screw 75 and a second actuation screw 80 may disposed. Firstactuation screw 75 may be coupled to a first actuation ramp 385. Secondactuation screw 80 may be coupled to a second actuation ramp 390. Rampedportions 395 may also be coupled to the first endplate 45 and secondendplate 50. First actuation screw 75 may be rotated to drive firstactuation ramp 385 to push ramped portion 395, which in turn may pushfirst endplate 45 to cause it to move outward on anterior side 35.Second actuation screw 80 may be rotated to drive second actuation ramp390 to push ramped portion 395, which in turn may push first endplate 45to cause to move outward on posterior side 40. In this manner, expansionon anterior side 35 and posterior side 40 may be independentlycontrolled. FIGS. 16A, 16B, and 17 illustrate the second endplate 50pivotally attached to ramped portion 395. FIG. 18 illustrates secondendplate 50 and ramped portion 395. Ramped portion 395 may be coupled tosecond endplate 50 to form an endplate assembly.

FIGS. 19-21 illustrate expandable fusion device 10 according to anotherembodiment. FIG. 20 is a cross-sectional view of FIG. 19 taken alongline c-c. FIG. 21 is a cross-sectional view of FIG. 20 taken along lined-d. As illustrated, the first actuation screw 75 and second actuationscrew 80 may be disposed through rear plate 380. First actuation screw75 and second actuation screw 80 may engage first shim 400 and secondshim 405, respectively. First shim 400 and second shim 405 may engage afirst pivot assembly 410 and second pivot assembly 415. First pivotassembly 410 and second pivot assembly 415 may pivot at first pivotpoint 420 and second pivot point 425, respectively. In the illustratedembodiment, first pivot assembly 410 and second pivot assembly 415 mayeach comprise pivot arms 416 coupled at first pivot point 420 and secondpivot point 425, respectively. First actuation screw 75 may be rotatedto cause first shim 400 to move in the direction of arrow 430 on FIG.20. First shim 400 may engage first pivot assembly 410 pushing it tocause first pivot assembly 410 to move outward in direction indicated byarrow 435. First pivot assembly 410 may lengthen as it moves outward,which in turn pushes on first endplate 45 and second endplate 50 causingthem to move away from one another, thus expanding on anterior side 35.Second actuation screw 80 may be rotated to cause second shim 405 tomove in the direction of arrow 430 on FIG. 20. Second shim 405 mayengage second pivot assembly 415 pushing it to cause second pivotassembly 415 to move outward in the direction of arrow 440. Second pivotassembly 415 may lengthen as it moves outward, which in turn pushes onfirst endplate 45 and second endplate 50 causing them to move away fromone another, thus expanding on posterior side 40.

FIGS. 22 and 23 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise first endplate 45 and second endplate 50. Cam member 450 may bedisposed between first endplate 45 and second endplate 50. Cam member450 may engage first endplate 45 and second endplate 50. Cam member 450may be rotatable. In some embodiments, cam member 450 may be rotated toadjust the angle between first endplate 45 and second endplate 50. FIG.23 illustrates expandable fusion device 10 after rotation of cam member450 to adjust the angle between the first endplate and the secondendplate 50 in accordance with present embodiments.

FIGS. 24 and 25 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise first endplate 45 and second endplate 50. A first cam member455 and a second cam member 460 may be disposed between first endplate45 and second endplate 50. First cam member 455 and second cam member460 may each engage first endplate 45 and second endplate 50. First cammember 455 and second cam member 460 may each be rotatable. In someembodiments, first cam member 455 may be rotated to force first endplate45 and second endplate 50 away from one another causing expansion onanterior side 35. In some embodiments, second cam member 460 may berotated to force first endplate 45 and second endplate 50 away from oneanother causing expansion on posterior side 40. Expandable fusion device10 may further comprise a linking plate 465 securing first endplate 45to second endplate 50. FIG. 24 illustrates expandable fusion device 10in a collapsed configuration. FIG. 25 illustrates expandable fusiondevice 10 in an expanded configuration after rotation of first cammember 455 and second cam member 460.

FIGS. 24 and 25 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise first endplate 45 and second endplate 50. A first cam member455 and a second cam member 460 may be disposed between first endplate45 and second endplate 50. First cam member 455 and second cam member460 may each engage first endplate 45 and second endplate 50. First cammember 455 and second cam member 460 may each be rotatable. In someembodiments, first cam member 455 may be rotated to force first endplate45 and second endplate 50 away from one another causing expansion onanterior side 35. In some embodiments, second cam member 460 may berotated to and second cam member 460 to force first endplate 45 andsecond endplate 50 away from one another causing expansion on posteriorside 40. Expandable fusion device 10 may further comprise a linkingplate 465 securing first endplate 45 to second endplate 50. FIG. 24illustrates expandable fusion device 10 in a collapsed configuration.FIG. 25 illustrates expandable fusion device 10 in an expandedconfiguration after rotation of first cam member 455 and second cammember 460.

FIG. 26 illustrates another expansion technique that may be used toactivate expansion of an expandable fusion device 10 (e.g., shown onFIG. 1) in accordance with present embodiments. As illustrated, acentral bar 470 may be disposed between endplate connectors 476, whichmay be coupled to corresponding endplates (e.g., first endplate 45 andsecond endplate 50 on FIG. 1). Central bar 470 may be moved to differentlocations between endplate connectors 476. Depending on positioning ofcentral bar 470 between endplate connectors 476, there may be variableexpansion of the endplates.

FIGS. 27-29 illustrate another expansion technique that may be used toactivate expansion of an expandable fusion device 10 (e.g., shown onFIG. 1) in accordance with present embodiments. For simplicity, onlyfirst endplate 45 is shown on FIGS. 27-29. Anterior wedge 475 may bepositioned on anterior side 35 and may engage first endplate 45. Forexpansion on anterior side 35, anterior wedge 475 may be pushed intofirst endplate 45 from anterior side 35. As illustrated, anterior wedge475 may engage a corresponding ramped surface 480 on first endplate 45to push first endplate 45 outward causing expansion on anterior side 35.Posterior wedge 485 may be positioned on posterior side 40 and may alsoengage first endplate 45. For expansion on posterior side 40, posteriorwedge 485 may be pushed into first endplate 45 from posterior side 40.As illustrated, posterior wedge 485 may engage a corresponding rampedsurface 488 on first endplate 45 to push first endplate outward causingexpansion on posterior side 40. In some embodiments, anterior wedge 475and posterior wedge 485 may be pushed into first endplate 45 in adirection generally transverse to a longitudinal axis of the expandablefusion device.

FIGS. 30-33 illustrate expansion of a corpectomy device 490 according tosome embodiments. As illustrated on FIG. 30, corpectomy device 490 maycomprise a first cutting endplate 495 and a second cutting endplate 500.First cutting endplate 495 and second cutting endplate 500 may beoperable to cut away vertebral bodies. A cam member 505 may be disposedbetween first cutting endplate 495 and second cutting endplate 500.Rotation of cam member 505 may force first cutting endplate 495 andsecond cutting endplate 500 away from one another causing expansion ofcorpectomy device 490. FIG. 31 illustrates corpectomy device 490disposed between adjacent vertebral bodies 15 and 20. Cam member 505 maybe rotated to adjust the angel between the first cutting endplate 495and second cutting endplate 500, as shown on FIG. 32. In someembodiments, corpectomy device 490 may be used to remove adjacentvertebral bodies 15 and 20 and then expanded to engage additionalvertebral bodies 510 and 515, as shown on FIG. 33.

FIGS. 34 and 35 illustrate another expansion technique that may be usedto activate expansion of an expandable fusion device 10 (e.g., shown onFIG. 1) in accordance with present embodiments. FIG. 34 iscross-sectional side view of an expandable fusion device 10 takenthrough anterior side 35 in accordance with present embodiments. Asillustrated, on FIG. 35 an anterior ramped translation member 520 may bedisposed between first endplate 45 and second endplate 50. Anteriorramped translation member 520 may be disposed on anterior side 35 (e.g.,shown on FIG. 1) of expandable fusion device 10. Anterior rampedtranslation member 520 may comprise a plurality of ramped portions 525,which may engage corresponding ramped portions 530 in the first endplate45 and second endplate 50. Anterior ramped translation member 520 may bemoved such that ramped portions 525 in engage ramped portions 530 tocause first endplate 45 and second endplate 50 to move away from oneanother. FIG. 35 is a cross-sectional end view of an expandable fusiondevice 10 in accordance with present embodiments. Anterior rampedtranslation member 520 is shown between first endplate 45 and secondendplate 50. A linkage assembly 535 may engage anterior rampedtranslation member 520. Linkage assembly 535 may comprise a central arm540 that engages anterior ramped translation member 520 and extensionarms 545. Extensions arms 545 may be engaged to first endplate 45 andsecond endplate 50 on posterior side 40 at pivot points 550 for anteriorexpansion. In some embodiments, linkage assembly 535 may be drivenposteriorly to increase posterior height H_(p). In some embodiments,first endplate 45 and second endplate 50 may comprise one or alternatepivot points 555. By setting extension arms 545 in alternative pivotpoints 555, for example, the relationship between anterior height H_(a),posterior height H_(p), and lordotic angle θ may be adjusted.

FIGS. 36 and 37 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise upper anterior endplate 560 and upper posterior endplate 565.For simplicity, the lower endplates are not shown in the embodimentillustrated on FIGS. 36 and 37. As illustrated, expandable fusion device10 may further comprise frame 570. A first arm 575 may be coupled toupper anterior endplate 560 and frame 570. First arm 575 may pivot atconnection point 580 with frame and also pivot at connection point 585with upper anterior endplate 560. First rack lever 590 may also bepivotally coupled to upper anterior endplate 560 at connection point585. First rack lever 590 and a second rack lever 600 may be pivotallycoupled to frame 570 at a connection point 595. Second rack lever 600may be pivotally coupled to upper posterior endplate 565 at connectionpoint 605. A second arm 610 may be coupled to upper posterior endplate565 at connection point 605 and may also be coupled to frame 570 atconnection point 615. Second arm 610 may pivot at connection point 615with frame and also pivot at connection point 605 with upper posteriorendplate 565. For expansion on anterior side 35, a gear member (notshown) may engage first rack lever 590 and then be rotated, thus causinganterior side 35 to raise, as shown on FIG. 37. For expansion onposterior side 40, a gear member (not shown) may engage second racklever 600 and then be rotated, thus causing posterior side 40 to raise.

FIGS. 38 and 39 illustrate expandable fusion device 10 according toanother embodiment. As illustrated, expandable fusion device 10 maycomprise a first endplate 45 and a second endplate 50. A pair ofinternal arms 616 and 620 may be disposed between first endplate 45 andsecond endplate 50, wherein each of internal arms 616 and 620 engage thefirst endplate 45 and the second endplate 50. Internal arms 616 and 620may be coupled to different endplates on opposite sides of theexpandable fusion device 10. For example, internal arm 615 may becoupled to first endplate 45 on anterior side 35, while internal arm 620may be coupled to second endplate 50 on posterior side 40. Rotation ofthe internal arms 616 and 620 about their respective connection pointspushes the first endplate 45 and second endplate 50 apart, resulting inan increase in height. As each of the internal arms 616 and 620 isconnected at a different side of the expandable fusion device 10,internal arms 616 and 620 may be independently rotated allowing forindependent expansion of anterior side 35 and posterior side 40. Any ofa variety of suitable techniques may be used for rotation of internalarms 616 and 620. By way of example, the internals arms 616 and 620 maybe directly rotated at their respective connection points to the firstendplate 45 and second endplate 50. Another rotation technique mayinclude moving one of the internal arms 616 and 620 outward manuallywhere it meets the endplate but is not connected to the endplate.

FIG. 40 illustrates expandable fusion device 10 according to anotherembodiment. In the illustrated embodiment, expandable fusion device 10may comprise independently adjustable anterior and posterior endplates,such as upper anterior endplates 625 and upper posterior endplates 630.The endplates, such as upper anterior endplates 625 and upper posteriorendplates 630, may have independent expansion mechanisms so facilitateindependent expansion on anterior side 35 and posterior side 40. In someembodiments, expansion of upper anterior endplate 625 may be actuated byfirst actuation screw 75 and upper posterior endplate 630 may beactuated by second actuation screw 80.

FIGS. 41 to 45 illustrate expandable fusion device 10 according toanother embodiment. The illustrated embodiment is similar to theembodiment of FIG. 40 except expansion may be facilitated through asingle hole 635. FIG. 41 is a perspective view of the expandable fusiondevice 10 in accordance with present embodiments. FIG. 42 is across-sectional view of expandable fusion device 10 taken along plane 42of FIG. 41, in accordance with present embodiments. As illustrated,expandable fusion device 10 may comprise a posterior ramped translationmember 640 and an anterior ramped translation member 645. Implant driver650, which may include an elongated shaft, may be disposed in hole 635,for example, with a threaded connection. Implant driver 650 may be movedforward or backwards to drive the translation member (e.g., posteriorramped translation member 640, anterior ramped translation member 645,or both) and, thus, push the endplates apart causing expansion. Distalend 655 of implant driver 650 may rotate to engage posterior rampedtranslation member 640, anterior ramped translation member 645, or both.FIG. 43 illustrates engagement of distal end 655 with posterior rampedtranslation member 640 in accordance with present embodiments. FIG. 44illustrates engagement of distal end 655 with anterior rampedtranslation member 645 in accordance with present embodiments. FIG. 45illustrates engagement of distal end 655 with both posterior rampedtranslation member 640 and anterior ramped translation member 645 inaccordance with present embodiments.

FIG. 46 illustrates another technique for expansion of an expandablefusion device 10, for example, shown on FIG. 40 comprising a separatelyexpandable anterior and posterior endplates arranged side by side. Inthe illustrated embodiment, a lordotic screw 660 may extend through rearplate 680 to engage posterior ramped translation member 640. Asillustrated anterior ramped translation member 645 may comprise anextension 670 that is configured to engage a contact surface 665 ofposterior ramped translation member 640. Lordotic angle θ may be set byrotating lordotic screw 660 to push posterior ramped translation member640 and, thus, move contact surface 665 away from extension 670.Expansion screw 675 may be disposed through rear plate 680 to engageanterior ramped translation member 640. Expansion screw 675 may driveanterior ramped translation member 645 causing it to push againstcorresponding endplates (e.g., upper anterior endplates 625 and upperposterior endplates 630 on FIG. 40) moving them outward to therebyincrease anterior height H_(a). Anterior height H_(a) may first beadjusted to a desired height greater than posterior height H_(p) andthen extension 670 may engage contact surface 665 such that anteriorramped translation member 645 pushed posterior ramped translation member640 causing posterior ramped translation member 640 to push againstcorresponding endplates (e.g., upper anterior endplates 625 and upperposterior endplates 630 on FIG. 40) moving them outward to thereby alsoincrease posterior height H_(p). In some embodiments (not illustrated),the expandable fusion device 10 may first rock into a desired lordosisand then utilize ramps to expand the expandable fusion device 10.

FIGS. 47-49 illustrate another technique for expansion of an expandablefusion device 10, for example, shown on FIG. 1. In the illustratedembodiment, a ramped translation member 685 may be disposed betweenfirst endplate 45 and second endplate 50. Ramped translation member 685may be in the general shape of spheroid, which may be oblate or prolate,for example. Ramped translation member 685 may be driven between thefirst endplate 45 and second endplate 50 to drive them apart to increaseheight. Lordosis may be achieved passively, in some embodiments, byallowing the first endplate 45 and/or the second endplate 50 to rock onthe ramped translation member 685, as seen on FIG. 49. The firstendplate 45 and second endplate 50 may contour to the lordosis of thedisc space.

FIGS. 50-54 illustrate another technique for expansion of an expandablefusion device 10, for example, shown on FIG. 1. In the illustratedembodiment, an actuation frame 690 may comprise actuation screws 695that drive ramps 700 disposed in the actuation frame 690. Asillustrated, actuation frame 690 may comprise a proximal end 705 and adistal end 710, which may be tapered to facilitate insertion into thedisc space, for example. Lateral sides 715 may couple the proximal end705 and distal end 710. Ramps 700 may be disposed in lateral sides.Actuation screws 695 may be disposed in proximal end 705. As illustratedon FIG. 50, the ramps 700 may be at least partially retracted intoactuation frame 690. Rotation of actuation screws 695 may extend ramps700 from actuation frame 690, as seen in FIG. 51. FIGS. 52-54 are endviews showing independent expansion of ramps on anterior side 35 andposterior side 40. FIG. 52 illustrates ramps 700 at least partiallyretracted in actuation frame 690. Actuation screw 695 on anterior side35 may be rotated to cause ramps 700 on anterior side 35 to extend fromactuation frame 690, as seen on FIG. 53. While not shown ramps 700 onanterior side 35 may engage endplates (e.g., first endplate 45, secondendplate 50 on FIG. 2) to cause an increase in anterior height H_(a).Actuation screw 695 on anterior side 35 may be rotated to cause ramps700 on anterior side 35 to extend from actuation frame 690, as seen onFIG. 54. While not shown ramps 700 on anterior side 35 may engageendplates (e.g., first endplate 45, second endplate 50 on FIG. 2) tocause an increase in posterior height H_(p).

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims. Althoughindividual embodiments are discussed, the invention covers allcombinations of all those embodiments.

What is claimed is:
 1. An expandable fusion device comprising: a firstendplate; first ramp frames that are pivotally coupled to the firstendplate; a second endplate; second ramp frames that are pivotallycoupled to the second endplate; a translation member assembly inengagement with the first ramp frames and the second ramp frames, thetranslation member assembly comprising ramps on a first side of theexpandable fusion device and ramps on a second side of the expandablefusion device; a first actuation member in engagement with thetranslation member assembly on the first side of the expandable fusiondevice; and a second actuation member in engagement with the translationmember assembly on the second side of the expandable fusion device. 2.The expandable fusion device of claim 1, wherein the first side is ananterior side, and wherein the second side is a posterior side.
 3. Theexpandable fusion device of claim 1, wherein the first ramp framescomprise a first anterior ramp frame and a first posterior ramp frame,and wherein the second ramp frames a second anterior ramp frame and asecond posterior ramp frame.
 4. The expandable fusion device of claim 3,wherein the first anterior ramp frame is pivotally coupled to the firstendplate on the first side of the expandable fusion device, wherein thefirst posterior ramp frame is pivotally coupled to the first endplate onthe second side of the expandable fusion device.
 5. The expandablefusion device of claim 3, wherein the second anterior ramp frame ispivotally coupled to the second ramp on the first side of the expandablefusion device, wherein the second posterior ramp frame is pivotallycoupled to the second ramp on the second side of the expandable fusiondevice.
 6. The expandable fusion device of claim 1, wherein protrusionsof the first endplate are engaged with mating features on the firstramped frames to form pivot points, and wherein protrusions on thesecond endplate are engaged with mating features on the second rampedframes to form pivot points.
 7. The expandable fusion device of claim 1,wherein the translation member assembly comprises: an anteriortranslation portion disposed on the first side of the expandable fusiondevice, wherein the anterior translation portion comprises one or moreramps; and a posterior translation portion in engagement with theanterior translation portion and disposed one the second side of theexpandable fusion device, wherein the posterior translation portion isslidable with respect to the anterior translation portion, wherein theposterior translation portion comprises one or more ramps.
 8. Theexpandable fusion device of claim 7, further comprising an anteriorramped end disposed on the first side of the expandable fusion deviceand at a proximal end of the expandable fusion device; and a posteriorramped end in engagement with the anterior ramped end, wherein theposterior ramped end is disposed on the second side of the expandablefusion device and at the proximal end of the expandable fusion device,wherein the posterior ramped end is slidable with respect to theanterior ramped end.
 9. The expandable fusion device of claim 8, whereinthe first actuation member comprises an actuation screw threaded throughthe anterior ramped end to engage the anterior translation portion,wherein rotation of the first actuation member in a first directioncauses the anterior ramped end and the anterior translation portion tomove towards one another.
 10. The expandable fusion device of claim 8,wherein the second actuation member comprises an actuation screwthreaded through the posterior ramped end to engage the posteriortranslation portion, wherein rotation of the second actuation member ina first direction causes the posterior ramped end and the posteriortranslation portion to move towards one another.
 11. The expandablefusion device of claim 1, wherein the first actuation member and thesecond actuation member are independently rotatable to selective adjustanterior height and posterior height of the expandable fusion device.12. An expandable fusion device comprising: a first endplate; a secondendplate; a translation member assembly disposed at least partiallybetween the first endplate and the second endplate, wherein thetranslation member assembly comprises: an anterior translation portiondisposed on an anterior side of the expandable fusion device, whereinthe anterior translation portion comprises one or more ramps; aposterior translation portion in engagement with the anteriortranslation portion, wherein the posterior translation portion isdisposed on a posterior side of the expandable fusion device, whereinthe posterior translation portion is slidable with respect to theanterior translation portion, wherein the posterior translation portioncomprises one or more ramps; an anterior ramped end disposed on theanterior side of the expandable fusion device and at a proximal end ofthe expandable fusion device; and a posterior ramped end in engagementwith the anterior ramped end, wherein the posterior ramped end isdisposed on the posterior side of the expandable fusion device and atthe proximal end of the expandable fusion device, wherein the posteriorramped end is slidable with respect to the anterior ramped end; a firstactuation screw threaded through a bore in the anterior ramped end andengaging the anterior translation portion; a second actuation screwthreaded through a bore in the posterior ramped end and engaging theposterior translation portion; anterior ramp frames disposed on theanterior side of the expandable fusion device that engage the ramps inthe anterior translation portion to transfer motion of the anteriortranslation portion to the first endplate and the second endplatethereby pushing the first endplate and the second endplate outwardincreasing an anterior height of the expandable fusion device; andposterior ramp frames disposed on the posterior side of the expandablefusion device that engage the ramps in the posterior translation portionto transfer motion of the posterior translation portion to the firstendplate and the second endplate thereby pushing the first endplate andthe second endplate outward increasing a posterior height of theexpandable fusion device.
 13. The expandable fusion device of claim 12,wherein anterior ramped end comprises a body portion comprising rampsand the bore of the anterior ramped end, and wherein posterior rampedend comprises a body portion and the bore of the posterior ramped end.14. The expandable fusion device of claim 12, wherein the anterior rampframes comprise a first anterior ramp frame pivotally coupled to thefirst endplate and a second anterior ramp frame pivotally coupled to thesecond endplate.
 15. The expandable fusion device of claim 12, whereinthe posterior ramp frames comprise a first posterior ramp framepivotally coupled to the first endplate and a second posterior rampframe pivotally coupled to the second endplate.
 16. A method ofinstalling an expandable fusion device, the method comprising:introducing the expandable fusion device into an intervertebral space,wherein the expandable fusion device comprises a proximal end, a distalend, an anterior side connecting the proximal end and the distal end,and a posterior side connecting the proximal end and the distal end,wherein the expandable fusion device has an anterior height on theanterior side and a posterior height on the posterior side; adjustingthe anterior height of the expandable fusion device independently fromadjustment of the posterior height; and adjusting the posterior heightof the expandable fusion device.
 17. The method of claim 16, wherein theanterior height is first adjusted prior to adjustment of the posteriorheight to set a lordotic angle of the expandable fusion device, andwherein the adjustment of the anterior height continued while theposterior height is adjusted.
 18. The method of claim 16, whereinadjusting the anterior height and adjusting the posterior heightcomprise adjusting separate anterior endplates and posterior endplates.19. The method of claim 16, wherein the adjusting the anterior heightcomprises rotating a first actuation screw to cause ramps on theanterior side of a translation member assembly to engage anterior rampframes forcing them to push against the anterior side of a firstendplate and a second endplate.
 20. The method of claim 16, wherein theadjusting the posterior height comprises rotating a second actuationscrew to cause ramps on the posterior side of a translation memberassembly to engage posterior ramp frames forcing them to push againstthe posterior side of a first endplate and a second endplate.